Color image forming apparatus and image forming method

Abstract

If a CPU is informed that “1200×1200 dpi” is selected from an input unit, the CPU switches a normal 8-bit RIP process with 600×600 dpi to a 1-bit RIP process with 1200×1200 dpi. Image data, which has become 1-bit data with 1200 dpi, is stored in a page memory. A pixel packing process unit executes (2×2) packing when the image data stored in the page memory is to be output from the page memory. The packed Y color image data is restored, without delay, to a normal pixel unit in a pixel division unit. The packed M color image data is restored, with a delay in a delay memory, to a normal pixel unit in the pixel division unit. The packed C color image data is restored, with a delay in the delay memory, to a normal pixel unit in the pixel division unit. The packed K color image data is restored, with a delay in the delay memory, to a normal pixel unit in the pixel division unit.

1 . A 4-series tandem type color image forming apparatus comprising: 
 a memory section that delays input image data; and    a control section that executes, when the image data is input to the memory section, a control to vary a resolution and a number of bits per pixel of the input image data in accordance with a memory capacity of the memory section.    
   
   
       2 . A 4-series tandem type color image forming apparatus comprising: 
 a first image data processing section that varies a data amount per pixel of input image data;    a second image data processing section that packs a plurality of pixels, or divides one pixel into a plurality of pixels, with respect to the image data, the data amount of which is varied by the first image data processing section;    a third image data processing section that restores the image data, which is packed or divided by the second image data processing section, to an original 1-pixel unit; and    a control section that switches processes in the first, second and third image processing sections.    
   
   
       3 . The color image forming apparatus according to  claim 2 , wherein the control section executes, when high-resolution image data is handled, a control to effect switching to a process of decreasing the data amount in the first image data processing section, a process of packing a plurality of pixels of the image data in the second image data processing section, and a process of dividing the image data packed by the third image data processing section into a 1-pixel unit.  
   
   
       4 . The color image forming apparatus according to  claim 2 , wherein the control section executes, when low-resolution image data is handled, a control to effect switching to a process of increasing the data amount in the first image data processing section, a process of dividing one pixel into a plurality of pixels in the second image data processing section, and a process of restoring the image data divided by the third image data processing section to a 1-pixel unit.  
   
   
       5 . The color image forming apparatus according to  claim 2 , further comprising a gradation processing section at a rear stage of the third image data processing section, which executes a gradation process to convert low-gradation image data to high-gradation image data.  
   
   
       6 . An image forming method for a 4-series tandem type color image forming apparatus, which forms an image by using a memory section that delays input image data, comprising: 
 varying a data amount per pixel of input image data in accordance with a capacity of the memory section;    packing a plurality of pixels, or dividing one pixel into a plurality of pixels, with respect to the image data, the data amount of which is varied;    restoring the image data, which is packed or divided, to an original 1-pixel unit; and    forming an image on the basis of the restored image data.